On any game you already own, the purchase button on the game's store page becomes the "purchase as a gift" button.

Add the game to your cart, then checkbox "GIFT THIS ORDER" and enter your friends' email below.

That's if you don't already own the game, if you do own it, like LegoDnD said, you can only gift it anyway.

The easiest way is to:

1) Add the game(s) to your cart
2) At checkout click the "GIFT THIS ORDER" box
3) At the email prompt Enter YOUR OWN Email
*This will send the Gift Code to your own email so it does not possibly get lost.*
4) Send your friend the Gift Code at anytime and they may retrieve the gift by clicking the REDEEM A CODE section under their acct name on GOG at the top of the screen and entering the Gift Code you gave them.

You will be able to see the Gift Code at anytime in your "Orders and Settings" section under your own acct. This will also show you when that Gift Code was redeemed and by what acct.

Edit: Be aware that you cannot combine gift orders. The entire order will be put under one Gift Code with all the games in that order - so complete each order going to different people separately.

Hope that helps. :)

To correct what LegoDnD has written, You can gift any game whether you own it or not. Just follow bjgamer's post just above mine. ^^^ :)

Also be aware of these limitations:
• To buy a gift, you must have spent $10 or more for your own account at least 3 months ago. If you hit this roadblock, open a support ticket and they might help you out.
• You can only buy one gift code for the same game once per 24 hours.
-- I cannot buy a game as a gift, why? - GOG Support Center

These measures were put in place to prevent fraud.